Detailed Description

Defines the Image Pyramid Object Interface.

A Pyramid object in OpenVX represents a collection of related images. Typically, these images are created by either downscaling or upscaling a baseimage, contained in level zero of the pyramid. Successive levels of the pyramid increase or decrease in size by a factor given by the VX_PYRAMID_SCALE attribute. For instance, in a pyramid with 3 levels and VX_SCALE_PYRAMID_HALF, the level one image is one-half the width and one-half the height of the level zero image, and the level two image is one-quarter the width and one quarter the height of the level zero image. When downscaling or upscaling results in a non-integral number of pixels at any level, fractional pixels always get rounded up to the nearest integer [R00125]. (E.g., a 3-level image pyramid beginning with level zero having a width of 9 and a scaling of VX_SCALE_PYRAMID_HALF results in the level one image with a width of \( 5 = \mathbf{ceil}(9*0.5) \) and a level two image with a width of \( 3 = \mathbf{ceil}(5*0.5) \). Position \( (r_N,c_N) \) at level \( N \) corresponds to position \( (r_{N-1}/\mathbf{scale}, c_{N-1}/\mathbf{scale}) \) at level \( N-1 \).

Retrieves a level of the pyramid as a vx_image [R01160], which can be used elsewhere in OpenVX. A call to vxReleaseImage is necessary to release an image for each call of vxGetPyramidLevel [R01161]. More...